This is the second resubmission of an R21 application to investigate the feasibility of conducting a population-based study of incident Alzheimer's disease in a Chicago community of Mexican Hispanic and non-Hispanic residents. Alzheimer's disease is a common and incurable disease for which few established risk factors have been identified. The Mexican Hispanic population, which is the largest and fastest growing ethnic minority in the US, has a high prevalence of conditions and risk factors that may place them at increased risk of Alzheimer's disease. The proposed investigative team possesses unique skills, experience, and resources to conduct community studies of incident Alzheimer's disease. However, there are significant challenges to conducting this type of study, including: 1) the relatively young age of the Mexican American population, resulting in potentially high costs of detecting Alzheimer's disease cases, and 2) social and geographical isolation of the Mexican community due to language, cultural and immigration differences, preventing full enumeration of older residents for the computation of prevalence and incidence rates. The proposed study will provide the necessary pilot data and community development to investigate the feasibility of conducting a risk-factor study of Alzheimer's disease in a geographically- defined Chicago community. To accomplish these goals the proposed study will: 1) analyze U.S. Census data to identify the Chicago communities best suited for the study, 2) further engage community support for the study, and 3) pilot an informant-based census of older Chicago residents and assess its completeness compared with U.S. census data. The proposed study will provide the necessary pilot data and community development to investigate the feasibility of conducting a complete enumeration of the older population for a longitudinal study of Alzheimer's disease and cognitive decline in a Chicago Mexican Hispanic community. [unreadable] [unreadable] [unreadable] [unreadable]